title: A comparison of Q-switched and long-pulsed alexandrite laser for the treatment of freckles and lentigines in oriental patients.
abstract: BACKGROUND
  Q-switched (QS) lasers are effective in the treatment of freckles and lentigines in Type I and II skin, with minimal adverse effects. Long pulsed (LP) lasers have been proposed to be more suitable for treatment of darker skin types.
  
  
  OBJECTIVE
  To investigate the efficacy and adverse effects of using QS or LP Alexandrite laser for the treatment of freckles and lentigines in Oriental patients.
  
  
  METHODS
  A prospective split-face study of 20 Chinese patients who were randomly assigned to undergo a single QS (50 nanosecond) or LP (100 microseconds) laser treatment to either side of their face was carried out. Two blinded physicians assessed clinical efficacy using visual analogue scales of pre- and post-treatment photographs. Subjective assessment was evaluated using questionnaires which detailed the degree of pain, erythema and edema sustained during treatment, and improvement and satisfaction levels at 4, 8, and 12 weeks.
  
  
  RESULTS
  There was statistically significant improvement in pigmentation (P < 0.05) in both groups throughout the study, with no statistical difference found between the groups. Postinflammatory hyperpigmentation was more frequently found after QS treatment (22%), compared to LP treatment (6%). Majority of patients reported moderate to marked improvement in pigmentation throughout the study with both pulse widths, and correspondingly high levels of satisfaction rates. More severe pain, erythema and edema were experienced during QS Alexandrite treatment.
  
  
  CONCLUSIONS
  LP Alexandrite is quick and effective, and carries a lower risk of adverse effects than QS Alexandrite, for the removal of freckles and lentigines in darker skin types.
authors.affiliation: Division of Dermatology, Department of Medicine, The University of Hong Kong, Hong Kong SAR, China.
authors.forename: S G Y
authors.initials: SG
authors.lastname: Ho
authors.forename: C K
authors.initials: CK
authors.lastname: Yeung
authors.forename: N P Y
authors.initials: NP
authors.lastname: Chan
authors.forename: S Y
authors.initials: SY
authors.lastname: Shek
authors.forename: H H L
authors.initials: HH
authors.lastname: Chan
mesh_terms: D000328:Adult; D002681:China; D005145:Face; D005260:Female; D006801:Humans; D053844:Lasers, Solid-State / Q000009:adverse effects / Q000627:therapeutic use*; D007911:Lentigo / Q000601:surgery; D008548:Melanosis / Q000601:surgery*; D008875:Middle Aged; D017060:Patient Satisfaction; D011446:Prospective Studies; D016896:Treatment Outcome